Various types of clamshell lathes are known in the art and can be utilized typically in industrial settings to mill a portion of a generally cylindrical pipe or tube. Clamshell lathes in some embodiments are designed as annular devices formed from semi-cylindrical halves connected together around a pipe to be milled. A stationary member of the clamshell lathe is temporarily fixed to the pipe. A rotatable member is operatively connected to the stationary member and is rotatable for example by an air, hydraulic, or electrically-operated motor operatively connected to the rotatable member. In some embodiments, the motor housing is connected to the stationary member and has a drive gear that engages gearing located on the rotatable member. A tool slide can be mounted on the rotatable member and is adapted to hold a milling or cutting tool for milling the pipe. The tool slide can include a feed mechanism that advances the tool slide and thus the cutting tool in a radial direction toward the pipe in incremental steps upon a predetermined revolution of the ring gear.
Examples of clamshell lathes include the following:
U.S. Pat. No. 4,739,685 relates to a lathe having a stationary member and a rotating gear member. A circular race member is connected to the gear member and held in position by means of bearings. Preferably, the bearings have longitudinal axes perpendicular to the top surface of the stationary member. Further, mounting brackets are utilized to reportedly quickly and easily mount a motor onto the stationary member. A two part tool module is also disclosed.
U.S. Pat. No. 4,939,964 relates to a portable machining lathe having a stationary member interconnected with a gear housing which covers a rotating gear member. A circular race member is connected to the gear member and held in place by means of a plurality of roller bearings. A tool module having a tool bit machines the work piece and automatically advances longitudinally along the work piece by means of an advance mechanism.
U.S. Pat. No. 5,549,024 relates to a clamshell machining lathe for cutting and finishing pipes in industrial settings comprising a split-ring assembly, including a clamping ring that is positioned about the pipe, and journaled to the clamping ring is a rotatable gear ring that supports a tool block carrying a cutting tool. The improvement reportedly resides in the bearing arrangement used to journal the gear ring to the stationary clamping ring. One face of the gear ring includes an annular groove whose side walls define a bearing race. The race is dimensioned to receive a plurality of roller bearings therein, the roller bearings being affixed to a planar surface of the clamping gear in a circumferential arrangement so as to fit into the bearing race when the gear ring is coupled to the clamping ring. The arrangement can reportedly support greater loads without canting, thus reportedly reducing wear on the moving parts.
U.S. Pat. No. 6,619,164 relates to a portable machining lathe for machining a pipe or similar workpiece. The lathe includes two semicircular members having a stationary section and a rotatable section. The two semicircular members are cooperatively connected by a hinge system on one end, and steel splice plates on the other. The hinge has a top bracket and bottom bracket on the stationary section of each member, and a male hinge and female hinge on the rotatable section of each member. The male and female hinges are cooperatively connected so that when the hinge is closed the two semicircular members form a complete annulus.